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MLXXX

Developing a simple petition for improved bitrates and increased spectrum allocation for DAB+ broadcasting in Australia

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1 hour ago, alanh said:

Go to live concerts with real unsampled unamplified sound for example at Qpac and the QSO has a new conductor.

You have such a limited memory, alanh. I have told you in the past that I attend orchestral concerts regularly.

I also happen to be a musician and currently perform in a number of different groups.  I hear live, unamplified, symphony orchestra instruments very frequently indeed.  

 

1 hour ago, alanh said:

I note that there are many broadcast streams at 48 kbit/s and you only complain of a single faulty one. What about the others.

It isn't "faulty". Its sound quality is quite typical for a low bitrate DAB+ broadcast. I see that you describe it as 48kbps, the nominal bitrate.

 

1 hour ago, alanh said:

Lets face it your petition is a failure, your views are not held by others.

I would remind you: there is no petition at this stage. The purpose of this thread is to gather together some points that might feed into a petition. 

As for others not holding my views, what an absurd statement! There have been many contributions to this forum over the years, from a variety of members, bemoaning the poor quality of many of the DAB+ services.  And in any case, official published test results indicate audible impairment perceived by test subjects for HE-ACC stereo at bitrates well in excess of 48kbps, let alone at the audio bitrate of a nominal 48kbps service.

Edited by MLXXX

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This should keep everyone happy or unhappy

Subjective and Objective Comparative Study of DAB+ Broadcast System

DAB+ @ "96kbps" sounds better than FM but they didnt check the actual audio bitrate.

Subjective testing HE-AACv2 in all but a couple of cases showed 56kbps actual bitrate is sub-good quality & worse than 96kbps & so on.

Their objective test ViSQOLAudio wasnt a good predictor of subjective quality except maybe for some pop genres.

 

 

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9 hours ago, Pesto Lovin' Man said:

This should keep everyone happy or unhappy

Subjective and Objective Comparative Study of DAB+ Broadcast System

Thanks very much, Pesto.  When I came across that recently published paper in my searches last night I glanced at it only briefly and mistook it for a paper I'd already read!

 

The paper is unusual in that part of it compares actual simulcast broadcasts, i.e. real life broadcasting of DAB+ with real life broadcasting of FM, albeit that no details are given as to the reception conditions for the FM.

I note that the more detailed results in the paper are for test HE-AAC encodings prepared by the research team, not live broadcast encodings.

 

9 hours ago, Pesto Lovin' Man said:

Subjective testing HE-AACv2 in all but a couple of cases showed 56kbps actual bitrate is sub-good quality & worse than 96kbps & so on.

For readers not familiar with absolute character subjective ratings using a 5-step scale:

 

Rating Label
5 Excellent
4 Good
3 Fair
2 Poor
1 Bad

 

In the paper, we can see mean opinion scores on page 8 for actual HE-AAC bitrates of 64kbps, 96kbps, 128kbps and 160kbps. Perusal of the histograms reveals that use of the lowest bitrate, 64kbps, led to scores of  around 3 or "fair".  [There is no mention of broadcast processing. These appear to have been straightforward encodings using the HE-AAC codec and nothing else. I note that it is very possible the 96kbps encoding would have used AAC-LC, leaving only the 64kbps encoding to rely on HE-AAC v1, i.e. spectral band replication.]

No part of the paper explores bitrates as low as 48kbps.  At page 7 of the paper it is stated: "Currently, the digital DAB+ multiplex in Poland offers radio programs at 6 bitrates: 64, 72, 96, 104, 112, and 128 kbps.". 

 

9 hours ago, Pesto Lovin' Man said:

DAB+ @ "96kbps" sounds better than FM but they didnt check the actual audio bitrate.

I see that in Figure 1 of the paper [a 2016 paper by Gilski & Stefanski, published in 2017 in the Archives of Acoustics (The Journal of Institute of Fundamental Technological of Polish Academy of Sciences)], the lowest nominal bitrate of the simulcasting DAB+ services (the rate for the regional service) slightly exceeded 96kbps:

Figure1-2016paperbyGILSKISTEFANSKI_zpsem

We in Australia would be envious of such high nominal bitrates. (The paper does not discuss differences between the overall data rate of the service, which appears to be what is quoted in Figure 1, and the bitrate of the embedded HE-AAC audio stream.)

An aside: I am beginning to think that for my sample files for Australian DAB+ vs FM I would be justified in using nominal DAB+ bitrates rather than actual bitrates. Doing so would align with the tendency to refer to real world DAB+ broadcasts by their nominal bitrate. I think that when members of the public read a statement about DAB+ radio such as "48kbps gives comparable to FM quality" it is reasonable for them to take that to mean the bitrate information displayed on their radio,  or the rate they might see publlshed on the internet if they search.  It's quite rare to see the actual audio bitrate of a DAB+ radio service disclosed.

 

64 kbps (actual) in Australia - what could be expected?

In Australia, the bitrate of 80kbps nominal is used by the ABC for programs that consist mostly of music. That bitrate roughly translates to 64kbps for the audio depending on how much bitrate is reserved for Program Associated Data. Here is an extract from details I posted on this forum recently (at http://www.dtvforum.info/index.php?/topic/96036-digital-radio-stations-list/&do=findComment&comment=2093845) for DAB+ in Brisbane:-

9C 206.352MHz CODEC Nominal Audio Comment
BR abc&SBS RADIO   bitrate bitrate  
ABC Classic FM HE-AAC v1 80 63.8  
ABC Country HE-AAC v1 80 47.6 large PAD
ABC Jazz HE-AAC v1 80 47.6 large PAD
Double J HE-AAC v1 80 47.6 large PAD

 

It is interesting to note the following comments in the paper, which appear at page 7:

Quote

When it comes to analysing speech or singing samples, the most important issue is the clarity and transparency of the audio material, since information contained in the voice must reach the listener. According to the subjects, the sound colour was significantly worse for samples coded at lower bitrates, especially 64kbps. This impression was given regardless of the music genre.

... Furthermore, as the listeners indicated, in case of signal samples from category 3-4, spatial attributes of sound, including spaciousness, sound perspective and localization stability, were reported as annoying or even unacceptable for bitrates lower than 128kbps. This effect was less common for electronic music pieces, as it was for classical or popular music.

Edited by MLXXX

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MLXXX,

Pity you don't understand the articles you quote

1. Why is talk 2 getting a worse rating than talk 1 when the bit rates are identical.

2. Where are the quality assessment graphs of all the samples using of FM as processed for pre-emphasis and then FM modulated and then received?

3. There is no mention of the audio processing applied to their DAB+ and FM signals prior to HE-AAC compression. Is it the same as used in Australia? Did they use any as it is common place in radio stations here. Our radio stations do not wish to pay for operators to control levels and commercial stations particularly want their station to be louder.

4.There is no references from the research institute in Germany which designed the family of AAC of compression standards.

I note that you have only complained about a faulty DAB+ stream where the radio station has been converting compressed signals back to analog and then recompressed using different algorithm. As a result there is link to lock the sample clocks together which causes the phasing effect you complained of. So since 4KQ is feeding an analog transmitter and hence speakers these effects will not be present. Digital radio stations have been warned not to do this.

There was no mention of the phasing effect you complained of. I note that the source signals are sampled at the same sample rate as used by DAB+ and there is no lossy compression prior to DAB+ encoding.

Even playing CDs which is lossless compression, the digital radio station needs to use a broadcast professional CD player which outputs its signals in AES 48 kHz sample rate signals. Internally the CD player will have to play the disc at 44.1 kHz to maintain the correct pitch and duration. This digital signal will have to be interpolated using a 48 kHz signal. A phase locked loop is used to lock the two oscillators. The CD sample rate is divided by 441 and the AES reference by 480. This means there is a phase comparison every 10 ms. This will stop the phasing effect you complain of. I note that other broadcasters don't have the phasing effect.

Have you complained to 4KQ about their poor sound quality yet?

I noticed you have not complained about the audio quality of any other broadcaster.

Alanh

 

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8 hours ago, alanh said:

1. Why is talk 2 getting a worse rating than talk 1 when the bit rates are identical.

One possibility is different sizes of PAD.

I'm sorry, alanh. I don't have the time or inclination to attempt to address the other points you raise other than to say again that sample rate conversion is a routine process. In my opinion it has no significance for this thread.

Within the context of a low or moderate bitrate psychoacoustic codec used for radio broadcasting, any alterations in sound quality are negligible that might arise from converting PCM source material at 44.1kHz (such as digital sound recovered from a red book CD disc) to 48kHz. If you don't believe me, I suggest you spend time with the freeware Audacity converting sample rates,* and see whether you can hear any differences.

_____________

* One exercise is to use Audacity to save a 48kHz sample rate file at a 192kHz sample rate [by temporarily changing the project sample rate]. Reload that saved file and displace it 1, 2 or 3 samples on the time line (your choice), and then save again but at a 48kHz sample rate. Compare the original 48kHz sample rate file waveform with the waveform resampled with a phase offset relative to the 48kHz sampling. The files will look the same shape in the editor apart from the time displacement, and you will find that they sound the same when played.  

Or set the project rate to 48kHz. Generate a 20kHz sine wave, and save it with a 192kHz project rate. Open that saved file and shift the waveform slightly on the timeline. Then set the project rate to 48kHz and save. The displaced phase is fully preserved when resampling to 48kHz. This flows from Nyquist. You can fully ascertain a waveform by sampling at no less than twice the highest frequency component of the waveform. In the physical world, there is no need to lock your ADC to the same phase as your DAC if a DAC is generating the waveform being sampled with the ADC and they both are operating at the same nominal sampling frequency but free-running. You get the same result. It also doesn't matter if you use a different nominal sample rate for your ADC (as long as it isn't too low a sample rate for your highest frequency component being sampled). The reconstructed waveshape  for the new digital file will be the same as it was for the old digital file, and will be indistinguishable when listening under double blind conditions. [Well if you use actual hardware DACs and ADCs there may be very slight differences from a conversion depending on the model of ADC or DAC. Conversions in the digital domain with software should be transparent to the human ear.]  At first blush this result is not at all intuitive for many people. Digital sampling is an extremely powerful technique!

 

It may help for an intuitive appreciation to consider that in nature a cycle of sound never exists in isolation. There is always an onset and a decay. [And if you try to use an electronic synthesizer to generate a single cycle you will still have the delay of the response of the human cochlea  to contend with.] As for digital to audio converters (DACs) and Analogue to Digital converters (ADCs) these oversample, i.e. operate at much higher rates than the nominal sample frequency. A decimation process can then provide a very nicely smoothed reconstructed waveform. The proof of the pudding however is in the eating: the 44.1kHz CD has been remarkably successful!
 

Edited by MLXXX

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On 4/17/2017 at 1:58 AM, MLXXX said:

I think another thing to consider to increase the bitrate available for music services would be to pare back the allocation for PAD. I'm not sure exactly how this works but I suspect that if the PAD bitrate were reduced it would still allow a basic slide to be displayed. It might just take longer for it to load when a user selects the service.

It does indeed seem to be the case that the image will load eventually. In the example below of a DAB+ service in Crakow, Poland (Kraków, Polski) called "FM+" the image took 47 seconds to load:

ImageAcquired47seconds-_Rate_bandscancra

Questions that come to mind include:

  1. Is 47 seconds too long for a user of a DAB+ service to wait for a 320 x 240 slide image to appear on the display of their DAB+ radio?
  2. What impact on sound quality would halving that time have?
  3. What impact on sound quality would dispensing with slides altogether have?

In relation to 3, if the nominal bitrate of the service were very low, then dispensing with slides altogether could noticeably improve the sound quality.  I note that DAB+ radios on sale in Australia have displays that show the name of the song (similar to FM radio RDS text) but rarely if ever have a display big enough to show a slide.

In relation to 2, if the nominal bitrate of the service were very low, then doubling the bitrate for slide acquisition could noticeably reduce the sound quality.

In the particular case of this DAB+ service provided in Poland (which happens to be the country in which the DAB+ FM comparisons were carried out for the 2016 paper that alanh raised queries about in this thread yesterday) the nominal bitrate was high for DAB+ radio, being at 144kbps. The bitrate for Program Associated Data of 6.8kbps represented only 5.2% of the nominal bitrate and would have had only a minor impact on the subjective sound quality. The bitrate available for the DAB+ audio itself (using the AAC -LC codec) was high for DAB+ broadcasting, being at 123.7kbps. These figures can be seen at 4m 24s into a Youtube video uploaded in September 2016. Here is detail from that time in the video:

Bit_Rate_bandscancracowpoland-t264_zpsuy

 

Here is a link to the full YouTube video, but set to start at 4m 24s into it. You can witness a significant delay before the slide is fully loaded and displayed:- 

 

 

Edited by MLXXX

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MLXXX,

You must be desperate using Uni student assignments to prove your case. Where is the Professor's assessment of their work? All the subjects were young, probably fellow students who are hardly average listeners. There age is well under the average Australian age.

When are you going to give examples of non-faulty Australian broadcasts which are fed to all mainland capital cities such as the ABC?

I don't know why you keep on about this. Brisbane is already using 3 DAB+ transmission channels when you add one each for Gold Coast, Sunshine Coast, Wide Bay, Darling Downs, and Lismore you have used all the 8 available channels. (TV uses all the others that DAB+ receivers tune). The ABC/SBS will have to use a single frequency network for Qld and another channel for Lismore as the programs are not identical particularly in Daylight saving in NSW.

So the the only way you can get more data rate is to push for DRM+ which is capable of 186 kbit/s however that will probably be used for multiple programs like the DAB+ services.

Your pole is a failure.

So forget it after you complain to 4KQ which will probably have to replace its sound library with a new one like 6IX did.

Give it a rest.

Alanh

 

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15 hours ago, alanh said:

Your pole is a failure.

Alanh, you've mispelled that word on this forum before. Please note the distinction in spelling: the north pole, an opinion poll.

However this thread is not a poll thread. It is for gathering together of points/information.

 

15 hours ago, alanh said:

You must be desperate using Uni student assignments to prove your case. Where is the Professor's assessment of their work? All the subjects were young, probably fellow students who are hardly average listeners. There age is well under the average Australian age.

The particular paper was brought to our attention by Pesto Lovin' Man.   I don't know the age ranges of the people who made up the panel of test subjects. The paper is rather light on, for detail, in a number of respects.

In terms of the off-air part of the study, the finding expressed in the paper is that the DAB+ broadcasts sounded subjectively better than the FM broadcasts. That part of the study does not assist me at all.  It might offer comfort though to broadcasters who use relatively high bitrates. 

I think there is a need to read between the lines with this paper. On the surface it says that according to the listening panel's individual subjective assessments (analysed collectively and statistically), real life DAB+ broadcasting [with whatever sound processing the broadcaster chose to use for that signal] surpassed simulcast real life FM broadcasting [with whatever sound processing the broadcaster chose to use for that signal] in Poland. But of course -- and this is not highlighted in the abstract for the paper or the summary part of the paper -- that was for relatively high bitrate DAB+ broadcasts. As for the FM, no detail was provided of reception conditions.

The nominal bitrates of the DAB+ broadcast services selected for the study were all at the high end for DAB+ broadcasting, when compared with DAB+ broadcasts in other parts of the world. Certainly the rates are very much at the high end compared with what is common in Australia. Even the lab-prepared sound files part of the study refers only to relatively high bitrates.  For that part of the study we are provided with a range of more detailed results, revealing serious issues with the AAC codec.  I consider that there is an implication from the laboratory files part of the study (not made explicit in the summary section of the paper) that DAB+ broadcasters need to pay attention to the bitrate of the encoded audio. It appears that the writers of the paper were content to indicate that the subjective sound quality of DAB+ broadcasting can compare favourably with FM broadcasting, without being too specific about bitrate (or for that matter the circumstances of reception of the FM signa). Or perhaps the paper was watered down at the last moment, on the advice of others, to avoid controversy. We are unlikely to ever know! 

For the part of the study dealing with unprocessed sound files of CD quality simply encoded to HE-AAC at different actual bitrates (as distinct from "nominal" bitrates), the reported results confirm what previously reported tests have revealed, that the subjective quality is less at lower bitrates. At the risk of repeating myself too many times, I will say again that although HE-AAC is a very efficient codec for modest bitrates it is by no means transparent at modest bitrates.  It does a remarkably good job under adverse conditions. It doesn't necessarily sound "good". It just sounds better than many competing codecs.

If Mr Trump gets his way setting a goal of a manned landing on Mars, a specialist low bit-rate codec for speech, such as a further refinement of extended HE-AAC, might be the choice for voice communications from the spacecraft back to earth, to wring out intelligible performance for human speech with the very low bitrates available for use over vast distances in outer space. However in a first world country like Australia, for local radio broadcasting, we should aim for a high standard, I suggest. Coding artefacts should be barely if at all noticeable most of the time. To achieve that, I think we need something of the order of 96kbps (actual), or better.

Edited by MLXXX

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There have been so many excellent posts to this forum in the past regarding DAB+ sound quality. Here is one I came across tonight while searching for something else. I think it explains the audible effect of reducing the bitrate, in a very easy to follow manner:-

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MLXXX,

If you read the link, the ages of the subjects is quoted. As I said you don't understand your google searches.

As I have already pointed out there are other factors which determine the sound quality from a broadcaster other than just bit rate tests in a lab in a University.

If the problems are as bad as you claim why can't you quote Australian examples, with broadcaster, date and time of transmission and a description of the sound and what is wrong with it.

You cannot hear any of these problems you keep quoting on syndicated Australian radio so how can you point out to an Australian broadcaster what is wrong with their digital sound.

 There is no likelyhood that any broadcasters will change their bit rate if you cannot demonstrate the problem with their received output on a set of studio quality speakers.

Have you complained to 4KQ yet?

Alanh

 

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10 hours ago, alanh said:

If you read the link, the ages of the subjects is quoted. As I said you don't understand your google searches.

I'm sorry, alanh; I missed that part of the paper, I must confess. I see that on page 4 of the pdf, this explanation appears, "The test was performed on a group of  45 people, aged between 18 and 25 years old. None of them had hearing disorders.".

You stated earlier in this thread, "All the subjects were young, probably fellow students who are hardly average listeners. There age is well under the average Australian age.".

 A quick internet search tells me that in 2011 the average Australian was 37. 

We could take it that most if not all of the participants could be expected to have their hearing intact in the range 15kHz to approaching 20kHz, an upper range of hearing acuity that the average 37 year old might well not have, and something that people in their 70s would almost certainly not have.

I wonder whether that made the restriction in the upper limit of broadcast FM sound to 15kHz more noticeable than it might have been for an older group. That does seem distinctly possible.

And it could be that certain artefacts of HE-ACC were more noticeable to these young adults than to older adults, such as SBR.

I am not aware of, and have not attempted to search for, usual or recommended practice in choosing ages of participants in tests for absolute transparency of psychoacoustic codecs at high bitrates, or for degree of subjective impairment in MUSHRA style testing of codecs at medium and low bitrates. 

I am of the opinion though that a broadcasting system should be designed to give good quality sound for young adults and for older people.

 

11 hours ago, alanh said:

If the problems are as bad as you claim why can't you quote Australian examples, with broadcaster, date and time of transmission and a description of the sound and what is wrong with it.

You cannot hear any of these problems you keep quoting on syndicated Australian radio so how can you point out to an Australian broadcaster what is wrong with their digital sound.

 There is no likelyhood that any broadcasters will change their bit rate if you cannot demonstrate the problem with their received output on a set of studio quality speakers.

Have you complained to 4KQ yet?

Alanh, I think you have misconstrued some of my comments, I have not suggested that any of the broadcasts are faulty. As best I can tell from casual listening, they are what is normal and to be expected where a moderate to low bitrate is employed.

 In recent listening  I have found that unusually poor sound for the nominal bitrate is generally explicable in terms of the allocation of an unusually high PAD. Conversely, unusually good subjective sound quality despite a low nominal bitrate can be due to a minimal PAD or the use of HE-AAC v2 rather than v1. For my ears I prefer a sacrifice in stereo image at lower audio bitrates through the use of Parametric Stereo: a less nuanced stereo effect but combined with a better basic sound quality.   

Your accusation "You cannot hear any of these problems you keep quoting on syndicated Australian radio", is incorrect.

I have made no personal complaint to any of the DAB+ broadcasters in relation to bitrates. I think the petition envisaged by this thread, if and when it materialises, will be more effiective than a phone call, email or letter from me to a broadcaster.

Having said that, some years ago I did complain in writing to a broadcaster for their use on-air of the description "CD quality" for their DAB+ broadcast. I received an apology advising me that the matter had been brought to the attention of the particular announcer who had, in ignorance, made the incorrect claim about the sound quality of the digital broadcast.

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You keep complaining that the audio bit rate is not high enough even in your last post.  In which programs, sounds and when are they is parametric stereo a problem? If parametric stereo is used the effect on the overall bit rate is tiny. I would rather have the stereo. Pity our broadcasters don't use stereo micing when there is more than one presenter.

Considering that Commercial Radio Australia hasn't used the "CD quality" in a very long time please drop this argument that there is insufficient data for the programs transmitted.

You still need to complain to 4KQ as they have a problem which is not evident on their AM program only their digital one.

So unless you can provide examples we can all assess please drop the poor sound quality tag. Remember that a lot of radios with speakers which are sold are more likely to have poor sound due to the speakers and the cabinet which contains them.

Alanh

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On 4/7/2017 at 8:12 PM, Audiofile said:

I think it's a good start... Empirical research is important... I think we'll need anecdotal reports as well as empirical research.

Hi Audiofile, just in case you or anyone else is wondering, I have by no means abandoned the idea of uploading some real life examples of DAB+ broadcasts. 

I have equipment for recording up to four analogue stereo sources simultaneously be they different model DAB+ radios using their line-out or headphone sockets , or FM or AM broadcasts. And, bypassing any analogue interface, I can capture a DAB+ digital transport stream using a USB dongle (RTL2832U).

I've done some preliminary testing comparing the subtle differences between different DAB+ radios but there is planning involved in not only deciding on which broadcasts to record with which radios, but how I might put the material together for a technically meaningful but easy to follow audio visual presentation on YouTube, possibly supplemented by direct links to uncompressed audio files. And then we would need a separate thread on this forum to give forum members the opportunity to comment. This would possibly be set up as a poll thread.

There is also the question of how many YouTube videos to prepare.  For example, it might make sense to to have one technical video comparing different DAB+ radios, another technical video comparing different FM or AM radios, and a third video inviting subjective comparisons for radio programs simulcast on DAB+ and FM or AM.  At this stage, my thinking is not to include any on-line streaming sources in the presentations.

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2 hours ago, MLXXX said:

I've done some preliminary testing comparing the subtle differences between different DAB+ radios but there is planning involved in not only deciding on which broadcasts to record with which radios, but how I might put the material together for a technically meaningful but easy to follow

Keep it simple. If youre not trying to show differences between radios then go with transport stream decoded by a proper fp decoder (better than the integer decoders used by most chipsets) and the best FM receier you have recorded through the best ADC you can lay your hands on. If the station also streams for a 3rd sample then capture that without reencoding and if you can arrange to have all three be the exact same material recorded a tthe same time even better.

Leave your "audio visual presentation on YouTube" until after youve collected and analyzed results.

You wont convince the irrationally enthusiastic but you dont have to hand him arguments.

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40 minutes ago, Pesto Lovin' Man said:

Keep it simple. If youre not trying to show differences between radios then go with transport stream decoded by a proper fp decoder (better than the integer decoders used by most chipsets) and the best FM receier you have recorded through the best ADC you can lay your hands on.

So by a proper decoder you'd mean something like this https://sourceforge.net/projects/aacstreamanalysis/ which uses faad2? Or is there something else that might somehow be better?

That also raises the question whether the FM should be captured by purely digital means, to keep a level playing field. I've found there are slight differences in the subjective sound quality between using a USB dongle for FM and using analogue capture of the output of the FM tuner in an AVR. And even with using a dongle and depending on the software used there are different settings for how to demodulate the FM signal, leading to very slight audible differences. I suspect I'll end up using a late model AVR FM tuner and an ADC. 

I have no problem with the ADC side of things. I use a Behringer Firepower FCA1616 Interface.  It's certainly good enough for analogue capture of FM radio and medium bitrate DAB+ radio. 

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Sorry fp = floating point. Most digital radio chips & phone or tablet apps use fixed point i.e. integer math to save CPU or DSP cost & power. That means minor rounding errors etc & so the decompressed audio is a little less accurate. Most desktops programs use a floating point decoder library but on Windows Id pick the Fraunhofer FhG AAC encoder/decoder just to save arguments later. If you want a fixed point decoder to compare with then Fraunhofer FDK AAC is supposed to be good.

Id stick qith a good analog FM receiver for FM although software decoding should theoretically be better. Or Id do both if youve got the hardware to grab the simulcasts in parallel. I wouldnt bother doing an analog capture of DAB since thats adding the unknown quantity of the radio/chipset & you want to minimise those unknowns.

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2 minutes ago, Pesto Lovin' Man said:

I wouldnt bother doing an analog capture of DAB since thats adding the unknown quantity of the radio/chipset & you want to minimise those unknowns.

Ordinarily I might agree but an enthusiastic member of this forum has suggested that new DAB+ radios produce noticeably superior sound to old DAB+ radios because of changes in the chips used (despite the fact that the relevant specifications for decoding HE-AAC remain unchanged).  This was partly behind my idea of a separate technical video just to compare the analogue outputs of different DAB+ radios. I would see that as a side issue. The main presentation would probably just use the DAB+ transport stream decoded with a floating point decoder. And I'd probably also make at least one example of the undecoded transport stream available for download (for geeks!).

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    • By Ron12
      According to my rough calculations which are based on publicly available data, DAB+ accounts for just under 20% of all radio listening in the 5 mainland state capitals (19.9%) by time spent listening.  What’s more, the whole-of-audience time spent listening to DAB+ (DAB+ audience x time spent listening) has increased by over 5% in each of the last two DAB+ surveys of 2016.
      As a comparison, the share of radio listening for DAB/DAB+ in the UK in the 2nd quarter of 2015 was 26.7%.  It was 31.2% the same time in 2016.  It was 19.1% in the 12 months to June 2012, so Australia’s 5 mainland capitals are only four years or so behind the UK.  Not bad given that Australia officially launched DAB+ 14 years after DAB was launched in London and 11 years after it was launched in the rest of the UK.
    • By MLXXX
      If anyone can supply me with a link to an official file considered to represent "FM quality", or an official definition, I'd be obliged. Over the years I've seen many references to "FM quality" but no actual definition, or sample file.

      My own experience is that using an older horizontally polarised external TV antenna connected to a medium quality AVR in a high signal strength metroplolitan reception area provides me with reception with a subjectively very good audio quality. For my ears, for a range of program material, it is markedly better than 48kbps DAB+, somewhat better than 64kbps DAB+. For my ears for classical music, it is noticeably better than 80kbps DAB+. I've found a modern car FM radio can also perform well, though with greater noise and subject to occasional glitches from multipath reception as the car moves along the road.
       
      The poor audio quality of real life DAB+ and real life DRM relative to FM radio in a high signal strength reception zone has been mentioned a number of times on this forum over the years. I do not however recall the following research paper having been mentioned or discussed. I happened across it today and thought some forum members beyond myself might find it to be of interest, despite it having been published back in 2013!
      _____________

       
      Research published in 2013 concluded that a very high bitrate was required to achieve FM quality. This was certainly much more than the 48 or 64kbps commonly used in Australia for DAB+, or the even lower audio bitrates commonly used internationally for DRM30 broadcasting. Access to the full paper requires payment of a fee or possible free access at the discretion of the authors. For the purpose of this thread I will merely rely on:
      1. The freely available abstract of the paper.
      2. Comments from two sources, being observations by people who have read the paper and prepared relatively formal remarks.

      Off we go then!
      1. The abstract, accessible at http://www.aes.org/e-lib/browse.cfm?elib=16969:-
      AES E-LIBRARY
      Perceived Audio Quality of Realistic FM and DAB+ Radio Broadcasting Systems
      The perceived audio quality of a digital broadcasting system (such as DAB+) is dependent on the type of coding and bit rates selected. Because of bandwidth constraints, the required number of channels, and conflicting auxiliary services, audio quality is sometimes degraded. In designing a broadcast system, it is necessary to have well-defined criteria for minimally acceptable quality. Two studies explored quality criteria and how quality degrades for various bit rates. For DAB+ the subchannel rate should not be less than the currently available maximum of 192 kbits/s for a stereo signal, which would be comparable to the quality of a modern FM system. Rates below 160 kbit/s can significantly degrade certain types of program material. To be truly perceptually transparent, bits rates of close to 300 kbits/s may be needed when using the current generation of coders.
      Authors:
      Berg, Jan; Bustad, Christofer; Jonsson, Lars; Mossberg, Lars; Nyberg, Dan
       
      Affiliations:
      Luleå University of Technology, Piteå, Sweden; Swedish Radio, Stockholm, Sweden; Swedish National Laboratory of Forensic Science - SKL, Linköping, Sweden
      (See document for exact affiliation information.)
        
      2. Comments at http://www.radiojackie.com/im/Digital%20radio%20AES%20research.doc

       
      DIGITAL RADIO – AES RESEARCH
       
      An important new study has been published in the Journal of the Audio Engineering Society: Perceived Audio Quality of Realistic FM and DAB+ Radio Broadcasting Systems.
       
      Many different music and speech samples were used in listening tests with the conclusion that a bit rate "close to 300 kbit/s" is required to avoid falling below FM quality.
      Neither UK-type DAB (from 1985) nor DAB+ (from 2007) are capable of offering this.
       
      This research is significant for two reasons.
      - For the first time, comparisons are made between digital radio and realistic FM radio.
      - Processed audio was used, rather than unprocessed sounds.
         Processed audio (e.g. 'Optimod') is universal in radio.
       
      Previous work, with unprocessed sounds, had suggested the necessity of 320 kbit/s
      to pass the perceptual transparency and statistical undetectability point.
      This was adopted by the BBC in 2010 for HD Sound in iPlayer.
       
      These results with processed audio dispel the notion that the sound quality presently possible via digital radio is found inferior by only a tiny minority of audiophiles.
       
      This new evidence, specifically examining everyday radio audio, supports the view that DAB has a role as a supplementary platform but could never prove satisfactory as the sole outlet over the airwaves.
       
       
      Trevor Brook - 11 November 2013
      Surrey Electronics  - radiofax.org - Editor: radiojackie.com

       
      3. Comments at http://www.engineeringradio.us/blog/2013/11/what-bitrate-is-needed-to-sound-like-analog-fm/
      What bitrate is needed to sound like analog FM?
      By Paul Thurst, on November 25th, 2013 7 comments 
      As it turns out, 300 kbp/s or greater.  At least in critical listening environments according to the paper titled Perceived Audio Quality of Realistic FM and DAB+ Radio Broadcasting Systems (.pdf) published by the Journal of the Audio Engineering Society. This work was done by group in Sweden and made various observations with different program material and listening subjects. Each person was given a sample of analog FM audio to listen to, then they listened to various audio selections which were using bit reduction algorithms (AKA CODEC or Compression) and graded each one.  The methodology is very thorough and there is little left for subjective interpretation.
      In less critical listening environments, bit rates of 160-192 kbp/s will work.
      ...
      [Note: The article immediately above goes on to provide a detailed table.]
      I personally am not at all surprised at the reported findings!
    • By alanh
      http://www.ebu.ch/files/live/sites/ebu/files/Publications/EBU-MIS%20-%20Digital%20Radio%20Report%202016.pdf
      The EBU is the European Broadcasting Union which public broadcasters (TV and Radio) over a population of over 500 million people.
      Alanh
    • By alanh
      http://www.theaustralian.com.au/life/personal-technology/lgs-digital-radio-smartphone-will-come-to-australia/news-story/7ca53d7a98f335074e00eaf137ff0cfc
      Alanh
    • By g12345567
      Thanks to Ozabargain.
      For those who may have missed this deal. Kmart currently have the Audiosonic Nora Mantle DAB+ portable radio on clearance for $9.
      Features:
      DAB+/FM radio
      Autoscan Function
      Preset and save up to 10 Radio stations each DAB+ and FM band.
      Alarm with sleep functionality
      LCD Display
      Rechargeable Lithium Battery (not removable)
      4-6 hours playtime
      Earphone jack (confirmed stereo out)
      Powered by AC/DC adaptor (Micro USB included)
    • By alanh
      http://www.digitalfernsehen.de/Vorarbeit-fuers-UKW-Ende-Deutschlandradio-verbessert-DAB-Empfang.127478.0.html
      Open in Google Chrome and get it to translate it
      German Kulture Digital radio is increasing its sample rate from 96 to 112 kBit/s and they are transmitting in 5.1 surround sound. http://translate.google.com.au/translate?hl=en&sl=de&u=http://www.deutschlandradiokultur.de/&prev=search shows they are using DAB+
      DRadio Knowledge from 88 to 96 kBit/s.
      Lets now see if you can tell the difference between this and your antique AM radio on the transmsitter fence line of 612 ABC Local radio.
      Alanh
    • By Ron12
      With Malcolm Turnbull announcing his intentions to free up some of the TV spectrum for other uses, e.g. mobile broadband, I would like to put forward some ideas on how this could be done.

      I have read elsewhere that MPEG4 would allow the same video to be encoded using half the bitrate, while DVB-T2 would allow the bitrate to be increased. On that basis, the number of channels required for any area would be reduced from 6 to 3 (already mentioned by others, e.g. here, This would free up 15 channels. Given the block structure of our channel allocation, this would mean freeing up three channels on VHF (could be used for expanding digital radio) and 12 on UHF (which could be used for freeing up 610-684 MHz for another digital dividend).
      What about H.265, which I've read requires half the bitrate again compared to H.264? Would this reduce the channels required per area to 2? This could free up another 5 channels, e.g. one channel from VHF and four from UHF, or we could dispense with the VHF band altogether for TV, freeing up 2 UHF channels, or just use them as unallocated channels. H.265 may be awhile off from being a viable alternative but we could start planning for it, moving to MPEG4 first, then switching to H.265.
    • By alanh
      http://www.pagegangster.com/p/KhoMa/#/page/1
      Alanh
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